Chlorine containing polyether sulfone polymers and preparation thereof

ABSTRACT

A novel, linear, chlorine-containing polyether-sulfone polymer excellent in flame retardancy, heat resistance, transparency, and water resistance, which is obtained by polymerizing at least one aromatic tri- or tetra-halide with at least one dialkali metal salt of a dihydric phenol, and a process for the preparation of this polymer. The polymer is represented by the following general formula: ##STR1## wherein X and Y stand for a hydrogen atom or a chlorine atom, with the proviso that at least one of X and Y is a chlorine atom, Q stands for a direct bond, --O--, --S-- or a divalent aliphatic or alicyclic hydrocarbon group in which the carbon number is an integer of from 1 to 6, m is 0 or 1, and n is an integer of from 10 to 1000.

DESCRIPTION

The present invention relates to a novel chlorine-containingpolyether-sulfone polymer excellent in the flame retardancy, heatresistance, transparency, and water resistance, which is obtained bypolymerizing at least one aromatic tri- or tetra-halide compound with atleast one dihydric phenol dialkali metal salt, and also to a process forthe preparation of this polymer.

A process for preparing a linear polyarylene-polyether-sulfone polymerby reacting a dihydric phenol dialkali metal salt with an activateddihalobenzenoid compound has been known (see Japanese Examined PatentPublication No. 42-7799). Furthermore, there has been proposed animproved process for the preparation of the above-mentioned polymer (seeJapanese Examined Patent Publication No. 45-21318, No. 46-18146, and No.46-21458).

Linear polyarylene-polyether polymers obtained according to theseprocesses are excellent in various properties such as the heatresistance at high temperatures, the mechanical characteristics, and thealkali resistance, and they are widely used in various fields.

However, the flame retardancy of these polymers is not completelysatisfactory as pointed out hereinafter. For example, when a film havinga thickness of 0.1 mm is ignited, burning is continued even after thefire source has been removed.

It also is known that a polyarylene-ether-sulfone polymer containing ahalogen atom on the aromatic nucleus can be obtained by reacting4,4'-dichlorodiphenylsulfone with a dialkali metal salt of anucleushalogenated bisphenol, as disclosed in the above-mentionedJapanese Examined Patent Publication No. 42-7799. However, in thisprocess, since the bisphenol having a halogen atom at the ortho-positionto the hydroxyl group of the bisphenol is used, the nucleophilicreactivity of the phenoxide is drastically reduced by the influence ofthe electron-attractive property of the halogen atom and the sterichindrance by the substitution at the ortho-position. Therefore, theprocess is disadvantageous in that a high temperature or a long time isnecessary for completion of the reaction. Moreover, the obtained polymeris readily colored and is not advantageous as a polymeric material.

In "Polymer", volume 18, page 360 (1977), T. I. Atwood teaches that achlorinated polyether-sulfone polymer can be obtained bymelt-polymerizing a compound represented by the following structuralformula: ##STR2## at such a high temperature as 310° C. In a polymerobtained by the polymerization conducted at such a high temperature asdescribed above, undesirable coloration or gelation is often caused.Moreover, since the melt polymerization technique is adopted, control ofthe viscosity is restricted. Namely, if it is intended to obtain apolymer having a high molecular weight, the viscosity of the reactionmixture should inevitably be increased, with the result that mechanicalstirring becomes difficult and the temperature in the reaction mixturebecomes uneven.

Furthermore, there is proposed a process in which3,3',4,4'-tetrachlorodiphenylsulfone is polymerized with4,4'-dihydroxydiphenylsulfone in the presence of anhydrous potassiumfluoride at a temperature of 240° C. for 23 hours (see JapaneseUnexamined Patent Publication No. 49-4800).

According to this process, a chlorinated polysulfone having a lowreducing viscosity of about 0.34 may be obtained without formation of agelation product. However, this process is not industriallyadvantageous, because a high reaction temperature and a long time arenecessary, and is not advantageous from the economic viewpoint, becausea fluoride which is more expensive than a hydroxide or carbonate shouldbe used at least in a stoichiometric amount. Moreover, since fluoride isused, a reaction vessel composed of glass or metal cannot be used.Therefore, this process is still insufficient in various points.

Under this background, we made researches with a view to obtainingpolymers while eliminating the foregoing defects. As the result, wefound that when (A) at least one aromatic tri- or tetra-halide isreacted with (B) at least one dihydric phenol dialkali metal salt underheating in the presence of an inert, highly polar solvent, the foregoingdefects are eliminated and an improved novel, substantially linear,chlorine-containing polyether-sulfone polymer represented by thefollowing general formula (I) is obtained: ##STR3## wherein X and Ystand for a hydrogen atom or a chlorine atom, with the proviso that atleast one of X and Y is a chlorine atom, Q stands for a direct bond,--O--, --S-- or a divalent aliphatic or alicyclic hydrocarbon group inwhich the carbon number is an integer of from 1 to 6, m is 0 or 1, and nis an integer of from 10 to 1000.

The novel, substantially linear polymer of the present invention has thefollowing excellent characteristics (effects).

(1) The chlorine-containing polyether-sulfone polymer of the presentinvention contains unreacted chlorine atoms only in an amount of 7.4% to13.9% by weight, but the flame retardancy of the polymer is veryexcellent and is ranked as "incombustible". For example, a film of thechlorine-containing polyether-sulfone polymer having a thickness of 0.1mm is burnt on a flame but if the flame is removed, the fire isextinguished in a moment.

(2) The polymer of the present invention has a high heat distortiontemperature and is excellent in thermal stability at high temperatures.

(3) In connection with the mechanical characteristics, the polymer ofthe present invention has a surprisingly high tensile strength (yieldstrength) which is comparable to the highest tensile strength amongengineering resins now available and comes next to the tensile strengthof reinforced plastics.

(4) Furthermore, the polymer of the present invention has a highhardness, and, therefore, the polymer can advantageously be used as ametal substitute.

(5) Moreover, the polymer of the present invention is excellent intransparency and has a good water resistance.

As is apparent from the foregoing description, the chlorine-containingpolyether-sulfone polymer of the present invention has various excellentcharacteristics. Furthermore, the process for the preparation of thispolymer according to the present invention has the followingcharacteristics (effects).

(1) If 3,3',4-trichlorodiphenylsulfone (hereinafter referred to as"C3DPS") or 3,3',4,4'-tetrachlorodiphenylsulfone (hereinafter referredto as "C4DPS") is used as the aromatic tri- or tetra-halide (hereinafterreferred to as "monomer (A)") and reacted with a dialkali metal salt ofa dihydric phenol (hereinafter referred to as "monomer (B)") accordingto the process of the present invention, a polymer can be obtainedwithout formation of a gelation product. In contrast, if C3DPS or C4DPSis gradually added to a solution of the above-mentioned dialkali metalsalt to effect the reaction according to the process disclosed in"Journal of Polymer Science", Part A-1, volume 5, pages 2376 to 2378(1967), a gelation product is formed with complete mixing of thesemonomers, and a valuable, substantially linear, chlorine-containingpolyether-sulfone polymer cannot be obtained.

(2) When the monomer (A) is reacted with the dialkali metal salt of themonomer (B) in the present invention, if the molar ratio between thesetwo monomers is changed, the difference over the reaction of4,4'-dichlorophenylsulfone (hereinafter referred to as "C2DPS") with adialkali metal salt of a dihydric phenol, disclosed in the abovereference, becomes prominent.

In order to obtain a preferred polymer, in each process, the molar ratiobetween the halide component and the dihydric phenol dialkali metal saltis 1:1. When C2DPS is used as the halide component, if the above molarratio is slightly increased or reduced, the molecular weight (the degreeof polymerization) is reduced. In contrast, when C3DPS or C4DPS is usedaccording to the present invention, if the molar ratio of C3DPS or C4DPSto the dihydric phenol dialkali metal salt is slightly increased above1:1, the molecular weight is reduced, but if this molar ratio isslightly reduced below 1:1, the molecular weight is increased. In viewof the foregoing, it is apparent that the monomer (A) used in thepresent invention is greatly different from C2DPS in the reaction mode.

As pointed out hereinbefore, the polymer of the present invention hasexcellent characteristics. Moreover, although the monomer (A) used inthe process of the present invention is a trifunctional compound ortetrafunctional compound, we found reaction conditions where the monomer(A) can act substantially as a bifunctional compound. We have nowcompleted the present invention based on this finding.

The polymer of the present invention can be obtained by reacting themonomer (A) with a dialkali metal salt of the monomer (B) under heatingin the presence of an inert, highly polar solvent.

(A) Monomer (A)

The monomer (A) that is used in the present invention is represented bythe following general formula (III): ##STR4## wherein X and Y stand fora hydrogen atom or a chlorine atom, with the proviso that at least oneof X and Y is a chlorine atom.

As specific examples of the monomer (A), there can be mentioned3,3',4-trichlorodiphenylsulfone (that is, C3DPS) and3,3',4,4'-tetrachlorodiphenylsulfone (that is, C4DPS). These compoundscan easily be prepared by using as the starting material at least onemember selected from chlorobenzene and o-dichlorobenzene.

(B) Dialkali Metal Salt of Monomer (B)

The dialkali metal salt of the monomer (B) that is used in the presentinvention is a dialkali metal salt of a monomer (B) represented by thefollowing general formula (II): ##STR5## wherein Q stands for a directbond, --O--, --S-- or a divalent aliphatic alicyclic hydrocarbon groupin which the carbon number is an integer of from 1 to 6, and m is 0 or1.

In the general formula (II), m is preferably 1, and Q is preferably adirect bond, an oxygen atom, a sulfur atom, a divalent aliphatichydrocarbon group in which the carbon number is up to 3, or a divalentalicyclic group in which the carbon number is 5 or 6.

As typical instances of the monomer (B), there can be mentioned2,2-bis(4-hydroxyphenyl)propane, 1, 1-bis(4-hydroxyphenyl)methane,1,2-bis(4-hydroxyphenyl)ethane, 1,1-bis(4-hydroxyphenyl)cyclohexane,4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl, and4,4'-dihydroxydiphenyl sulfide. Among these monomers (B),2,2-bis(4-hydroxyphenyl)propane is especially preferred from theviewpoints of cost and reactivity.

The dialkali metal salt of the monomer (B) is prepared from the monomer(B) and an alkali metal compound, described hereinafter, separately fromthe polymerization, or in the polymerization system before thepolymerization or simultaneously with the polymerization. Accordingly,by the term "dihydric phenol dialkali metal salt", it is indicated thatthe monomer (B) component is in effect reacted in the form of a dialkalimetal salt. For example, when an alkali metal carbonate is used as thealkali metal compound, it sometimes happens that the monomer (B) andalkali metal carbonate first form a monoalkali metal salt of thedihydric phenol, the monoalkali metal salt reacts with the monomer (A)before formation of the dialkali metal salt, and, then, the remainingphenol forms the alkali metal salt and the polymerization is performed.Thus, it sometimes happens that the formation of the salt and thepolymerization cannot clearly be distinguished from each other. In thiscase, it can be said that the dihydric phenol acts in effect as thedialkali metal salt, though the details are not apparent even to us.This case is also included in the scope of the present invention.

As the alkali metal of the alkali metal compound, there can be mentionedlithium, sodium, and potassium. In view of reactivity and cost, sodiumand potassium are preferred. As the alkali metal compound, there can bementioned hydroxides, carbonates, and hydrogencarbonates. Hydroxides andcarbonates are especially preferred. Namely, sodium hydroxide, potassiumhydroxide, sodium carbonate, and potassium carbonate are preferably usedas the alkali metal compound.

(C) Inert, Highly Polar Solvent

The inert, highly polar solvent that is used in the present invention isa solvent for the monomer (A), the monomer (B), and the formed polymerand dissolves limited amounts of the dialkali metal salt of the monomer(B) and the alkali metal carbonate or hydrogencarbonate underpolymerization temperature conditions. If the solvent dissolves thesealkali metal salts, the polymerization reaction can be advancedsmoothly. The fact that the solvent dissolves a limited amount of thealkali metal carbonate means that formation of the dialkali metal saltof the monomer (B) from the monomer (B) and the alkali metal carbonateor hydrogencarbonate is advantageously performed. Especially in thepresent invention, using the monomer (A) containing chlorine atomsdiffering in reactivity, undesirable side reactions are controlled and asoluble polymer is advantageously obtained.

For the foregoing reasons, in the present invention, a sulfoxidecompound and a sulfone compound are preferably used as the inert, highlypolar solvent. As preferred examples of the sulfoxide or sulfonecompounds, there can be mentioned compounds represented by the followinggeneral formula (IV): ##STR6## wherein R and R', which may be the sameor different, stand for a monovalent aliphatic hydrocarbon or aromatichydrocarbon group having no aliphatic unsaturated linkage of thealpha-carbon atom and having preferably up to 8 carbon atoms, or R andR' are bonded together to form a divalent alkylene group, and x is 1 or2.

As R and R' in the general formula (IV), there can be mentioned loweralkyl groups such as methyl, ethyl, propyl, n-butyl, and isobutylgroups; aryl groups such as a phenyl group; and a divalent alkylenebridge as in thiophene oxide or dioxide.

As preferred examples of the inert, highly polar solvent to be used inthe present invention, there can be mentioned dimethylsulfoxide,diethylsulfoxide, dimethylsulfone, diethylsulfone,tetramethylenesulfone, and diphenylsulfone. Dimethylsulfoxide,dimethylsulfone, and tetramethylenesulfone are especially preferred.

(D) Polymerization Methods

The polymer of the present invention can be prepared according to any ofthe three polymerization methods described below.

According to the first polymerization method, the dialkali metal salt ofthe monomer (B) is reacted with the monomer (A) in the inert, highlypolar solvent. This method involves (a) an embodiment in which ananhydrous dihydric phenol dialkali metal salt prepared in advance in adifferent reaction system is used and reacted with the monomer (A) inthe inert, highly polar solvent, (b) an embodiment in which the monomer(B) is first reacted with an alkali metal hydroxide in the presence ofthe inert, highly polar solvent, water present in the reaction system isremoved by azeotropic distillation with an inert azeotropic solvent toproduce a substantially anhydrous state, and the monomer (A) is thenadded to effect the reaction, and (c) an embodiment in which a hydratedparticulate dialkali metal salt of the monomer (B) is heated in theinert, highly polar solvent and an inert azeotropic solvent to removewater by azeotropic distillation and the monomer (A) is then added toeffect the reaction.

According to the second polymerization method, a substantially equimolarmixture of a hydrated particulate dialkali metal salt of the monomer (B)and the monomer (A) is heated in the presence of the inert, highly polarsolvent and an inert azeotropic solvent to remove water of hydration byazeotropic distillation to produce a substantially anhydrous state andthe main polymerization reaction is carried out during or after theabove azeotropic distillation.

According to the third polymerization method, a mixture of the monomer(A), the monomer (B), and the alkali metal carbonate orhydrogencarbonate is heated with the inert, high polar solvent and inertazeotropic solvent to form the dialkali metal salt of the monomer (B),formed water is removed by azeotropic distillation, and the mainpolymerization reaction is carried out during or after the azeotropicdistillation.

In each of the foregoing methods, it is necessary that thepolymerization reaction be carried out in the substantially anhydrousstate. In many cases, water is present in the polymerization system. Forexample, water provided by the use of an aqueous solution of an alkalimetal hydroxide, water formed on production of the salt, and waterpresent in the solvent are present in the polymerization system. Suchwater should be removed from the polymerization system before thepolymerization or during the advance of the polymerization, but it ispreferred that water be removed prior to occurrence of the mainpolymerization reaction. As means for removing water, there ispreferably adopted azeotropic distillation using an inert azeotropicsolvent capable of forming an azeotropic mixture with water.

The inert azeotropic solvent should be a solvent incapable of reactingwith the monomer (A), the monomer (B), and the dialkali metal salt ofthe monomer (B). As the inert azeotropic solvent, there are preferablyused aromatic hydrocarbons such as benzene, toluene, xylene,chlorobenzene, and o-dichlorobenzene and nucleus-halogenated aromatichydrocarbons (having 1 or 2 halogen atoms).

The amount used of the inert azeotropic solvent differs to some extentaccording to the polymerization method adopted, but ordinarily, theinert azeotropic solvent is used in an amount of up to 15 parts byweight, preferably 0.5 to 10 parts by weight, per part by weight of theinert, highly polar solvent. The inert azeotropic solvent may be used ina larger amount, but in this case, the polymerization becomesdisadvantageous because a reaction vessel having a large capacity shouldbe used, the productivity is reduced, and a long time is required forremoving the excessive portion of the inert azeotropic solvent. On theother hand, if the amount of the inert azeotropic solvent is too small,removal of water by the azeotropic distillation becomes difficult, andthe reaction mixture becomes a homogeneous solution and an undesirableside reaction sometimes takes place between water and the monomer (A).

The respective polymerization methods will now be described in detail.

When the polymerization is carried out according to the firstpolymerization method, after the reaction system is renderedsubstantially anhydrous, the dialkali metal salt of the monomer (B) ismixed and contacted with the monomer (A). Gradual addition of themonomer to a solution of the dialkali metal salt of the monomer (B) at ahigh temperature should be avoided because a gelation product is formed.The difference between the known process using a bifunctional halide andthe process of the present invention using the monomer (A) resides inthis point.

When the monomer (A) is gradually added to a solution of the dialkalimetal salt of the monomer (B), a gelation product is formed. The reasonis considered to be as follows.

In case of, for example, C4DPS, the chlorine atom at the para-positionto the SO₂ group has a high reactivity (activity), but the reactivity ofthe chlorine atom at the meta-position is low. However, if theconcentration of the monomer (A) is considerably lower than theconcentration of the dialkali metal salt of the monomer (B), namely ifthe concentration of the chlorine atom at the para-position to the SO₂group is considerably lower than the concentration of the phenoxide, thechlorine atom at the meta-position to the SO₂ group participates in thereaction with the phenoxide, resulting in formation of branches.Accordingly, it is considered that when the monomer (A) is graduallyadded, gelation is caused in the foregoing manner.

Therefore, when the polymerization is carried out according to the firstpolymerization method, attention should be paid to the mixing andcontacting manner.

According to one embodiment, a solution of the dialkali metal salt ofthe monomer (B) is cooled below 120° C. The monomer (A) is added at onetime to this solution. In the inert, highly polar solvent, the dialkalimetal salt of the monomer (B) is precipitated under cooling, and theamount dissolved of the dialkali metal salt of the monomer (B) islimited. Moreover, the reaction speed is reduced by cooling and thereaction with the chlorine atom at the meta-position is controlled. Thecooling temperature is below 120° C., preferably below 100° C. Themonomer (A) should be added while maintaining this temperature.

According to another embodiment, the monomer (A) is added at one time toa heterogeneous dispersion of the dialkali metal salt of the monomer (B)in a liquid mixture of the inert azeotropic solvent and the inert,highly polar solvent. According to this embodiment, since the dialkalimetal salt of the monomer (B) is not substantially dissolved, it ispossible to cause the reaction simultaneously with the mixing. It hasbeen found that by adoption of this mixing method, occurrence of thegelation in the solution can be avoided. The excessive amount of theinert azeotropic solvent is removed by azeotropic distillation, and thepolymerization reaction is carried out in the state where the liquidphase is concentrated to such an extent that the dialkali metal salt ofthe monomer (B) has a solubility in the liquid phase. In thisembodiment, the temperature at the time of addition of the monomer (A)is preferably lower than 140° C. and especially preferably lower than120° C. The weight ratio of the inert azeotropic solvent to the inert,highly polar solvent at the time of addition of the monomer (A) ispreferably in the range of from 0.5/1 to 10/1 and especially preferablyin the range of from 0.5/1 to 2/1.

In the case where the polymer of the present invention is preparedaccording to the second method, it is preferred that the weight ratio ofthe inert azeotropic solvent to the inert, highly polar solvent be inthe range of from 1/1 to 10/1, especially in the range of 2/1 to 5/1.When this method is adopted, water of hydration in the dialkali metalsalt of the monomer (B) is removed from the reaction system byazeotropic distillation with the inert azeotropic solvent beforeoccurrence of the main polymerization reaction to produce asubstantially anhydrous state. It is preferred that the inert azeotropicsolvent be then removed by distillation to such an extent that thedialkali metal salt of the monomer (B) has a substantial solubility inthe solution, and the polymerization reaction be then caused to advance.

It was found that when the polymer is prepared according to this method,the ratio of the inert azeotropic solvent to the inert, highly polarsolvent is important. Namely, if the weight ratio of the inertazeotropic solvent to the inert, highly polar solvent is lower than 1/2,sufficient removal of water in the reaction system becomes difficult. Inan extreme case, the reaction system becomes substantially homogeneous.Accordingly, an undesirable side reaction takes place between water andthe monomer (A) in the reaction system to form a phenol. Formation ofthe phenol results in breakage of the stoichiometric ratio between themonomers (A) and (B) and the adjustment of the degree of polymerizationbecomes impossible.

This method is advantageous in that since the dialkali metal salt isfinely divided, it is finely dispersed in the polymerization solution.Accordingly, dehydration can easily be accomplished, and thepolymerization is accomplished after the dehydration. Furthermore, sinceall the monomers and the solvents are charged at the start,incorporation of undesirable oxygen (air) in the reaction system duringthe polymerization is prevented, and, therefore, a polymer having abeautiful color is obtained.

In the case where the polymer of the present invention is preparedaccording to the third polymerization method, the monomer (A) is reactedwith the monomer (B) in the presence of an alkali metal carbonate orbicarbonate in a liquid mixture of the inert azeotropic solvent and theinert, highly polar solvent.

According to this method, the alkali metal carbonate or bicarbonate isreacted with the monomer (B) to form a phenoxide. This phenoxide isreacted with the monomer (A) to effect the polymerization. However, itis not clear whether the dialkali metal salt of the monomer (B) isformed by the reaction of the monomer (B) with the alkali metalcarbonate or bicarbonate before occurrence of the polymerization orformation of the phenoxide is conducted simultaneously with thepolymerization reaction.

In carrying out the polymerization according to this method, the ratioof the inert azeotropic solvent to the inert, highly polar solvent atthe time of initiation of the polymerization is ordinarily such that theamount of the inert azeotropic solvent is 0.5 to 5 parts by weight,preferably 0.5 to 3 parts by weight, per part by weight of the inert,highly polar solvent. If the amount of the inert azeotropic solvent issmaller than 0.5 part by weight per part by weight of the inert, highlypolar solvent, removal of formed water becomes difficult and no goodresults are obtained.

(E) Polymerization Conditions and Post Treatment

(1) Usage (Reaction) Ratios

The amount of the monomer (A) used in preparing the polymer of thepresent invention is 98 to 105 moles, preferably 100 to 102 moles, per100 moles of the dialkali metal salt of the monomer (B). If the amountof the monomer (A) is too small and below this range, undesirablebranching is caused in the formed polymer, and even if a gelationproduct is not formed, the molecular weight is extremely increased andthe physical properties of the polymer are degraded.

When an alkali metal carbonate or bicarbonate is used as in the casewhere the polymer is prepared according to the third polymerizationmethod, it is preferred that the monomer (A) be used in an amount of 98to 105 moles, especially 100 to 102 moles, per 100 moles of the monomer(B). The amount used of the alkali metal carbonate or bicarbonate isdetermined based on the amount of the monomer (B).

In the case where the alkali metal carbonate is used, it is preferredthat the amount used of the alkali metal salt be 1 to 2 moles,especially 1.05 to 1.2 moles, per mole of the monomer (B).

In the case where the alkali metal hydrogencarbonate is used, it ispreferred that the amount used of the alkali metal hydrogencarbonate be2 to 4 moles, especially 2.1 to 2.5 moles, per mole of the monomer (B).

As is apparent from the foregoing description, use of the alkali metalcarbonate or hydrogencarbonate in a slightly excessive amount isallowed, though this is not allowed in case of an alkali metalhydroxide.

(2) Usage Ratio of Inert, Highly Polar Solvent

The amount used of the inert, highly polar solvent is ordinarily 20 to1000 parts by weight per 100 parts by weight of the polymer to beformed, but in view of the easiness in stirring of the polymer solution,the post treatment after the polymerization, or the recovery of theformed polymer, it is preferred that the inert, highly polar solvent beused in an amount of 50 to 300 parts by weight per 100 parts by weightof the polymer to be formed.

(3) Polymerization Temperature

The polymerization temperature to be adopted for the preparation of thepolymer of the present invention differs according to the kind of theinert, highly polar solvent used, but the polymerization temperature isordinarily 120° C. to 250° C. and it is preferred that thepolymerization be carried out at a temperature of 130° C. to 200° C.,especially 140° C. to 180° C. In the case where the polymerizationtemperature is too high, if a sulfoxide compound such asdimethylsulfoxide is used as the inert, highly polar solvent, the formedpolymer is often colored by the decomposition of the solvent.Accordingly, the polymerization should be carried out at a temperaturelower than the decomposition temperature of the solvent, and if asulfoxide compound is used as the inert, highly polar solvent, it ispreferred that the polymerization temperature be lower than 160° C. Onthe other hand, if the polymerization is carried out at too low atemperature, the reaction speed is low and a long time is required forcompletion of the polymerization, and therefore, the process becomesdisadvantageous from an economic viewpoint. Furthermore, if thepolymerization temperature is too low, a polymer having a high molecularweight can hardly be obtained.

(4) Atmosphere

If oxygen (air) is present in the reaction system, coloration of theformed polymer is caused, and formation of a polymer having a highmolecular weight is often inhibited. Accordingly, it is necessary thatthe atmosphere of the reaction system be sufficiently replaced with aninert gas (nitrogen is preferred from an economic viewpoint) beforeinitiation of the polymerization and the polymerization be carried outin an inert gas atmosphere.

(5) Dehydration

If water is separated from the azeotropic mixture of the inertazeotropic solvent and water and only the inert azeotropic solvent isrecycled to the reaction system, the amount of water in the reactionsystem can be reduced to the saturation amount of water in the inertazeotropic solvent. Further dehydration can be accomplished byperforming the azeotropic distillation of the inert azeotropic solventand water while not recycling the separated inert azeotropic solvent tothe reaction system.

(6) Stopping of Polymerization

If the reaction system is cooled, the polymerization is substantiallystopped because of solidification. Furthermore, the polymerization canbe stopped by dilution with a solvent for the formed polymer, or byadding a non-solvent to the reaction mixture to precipitate the formedpolymer. Moreover, an alkyl halide such as methyl chloride or tert-butylchloride or an active halide compound such as4,4'-dichlorodiphenysulfone is added to the obtained solution containingthe formed polymer after completion of the polymerization and is reactedwith the terminal phenoxide of the polymer to cap the polymer ends,whereby the polymerization is stopped.

(7) Separation and Purification of Polymer

Known methods customarily adopted for separation and purification ofordinary polymers may be adopted for separating and purifying theobtained polymer after completion of the polymerization. For example, asolvent for the polymer, which is a non-solvent for the formed salt,such as chlorobenzene, is added to the polymer solution to dilute thepolymer solution, and the precipitated salt is separated by filtration.Then, a non-solvent for the polymer, such as methyl alcohol, is added tothe polymer solution, whereby the polymer can be separated. Thepurification is accomplished by repeating the above operation. Then, thepolymer is heated under reduced pressure to distill off the solvent leftin the polymer, whereby the purified polymer can be obtained.

(F) Properties and Uses of Polymer

The so-purified polymer of the present invention is in the form offoamed fibers having a white to light yellow color (a molded article ofthe polymer has a light yellow to light brown color). Most of polymersobtained according to the present invention are soluble in organicsolvents such as chlorobenzene, methylene chloride, chloroform,tetrachloroethane, and dimethylformamide. The polymer of the presentinvention is represented by the above-mentioned formula (I). When thepolymer is used as a molding material, the polymerization degree (n) ispreferably 20 to 200, though the preferred polymerization degree differsto some extent according to the structure of the recurring units.

In the case where the molecular weight of the polymer of the presentinvention is low (that is, the polymerization degree is low), themechanical strength is not sufficient if it is used as a moldingmaterial, but when it is mixed with other resin, it can act as a flameretardant imparting a flame retardancy to the resin. When alow-molecular-weight compound is used as a flame retardant, a problem ofbleeding or migration often arises, and especially if thelow-molecular-weight compound is used in a large amount, the mechanicalproperties of the resin are often drastically reduced. This problem,however, can be solved by using a polymer (inclusive of apolycondensate) having a relatively high molecular weight. If a certainpolymer of the present invention having a low polymerization degree isincorporated in a commercially available polymer (for example, apolysulfone resin), an excellent flame retardancy can be given to thepolymer without degradation of the transparency or heat distortiontemperature of the polymer and without substantial changes of othermechanical properties. The polymer that is used for this purpose is notlimited to a polymer having a relatively low polymerization degree (apolymer having a relatively high polymerization degree may be used as aflame retardant), but a surprisingly high additive effect can be exertedeven by a polymer having a relatively low polymerization degree.

As pointed out hereinbefore, a polymer of the present invention having arelatively high molecular weight has a very good flame retardancy, andmost of polymers of the present invention having a relatively highmolecular weight are excellent in the transparency and water resistance.They also have a high heat distortion temperature and are excellent inthermal stability at high temperatures. Moreover, they are excellent invarious mechanical properties, the tensile strength and hardness beingespecially high.

The polymer of the present invention can be molded according to knownmolding methods customarily adopted for other resins of this type.Additives used for ordinary synthetic resins, such as processabilityimproving agents, fillers (glass fibers, inorganic materials, and carbonfibers), antistatic agents, and colorants may be incorporated into thepolymer of the present invention.

The polymer of the present invention or a composition formed byincorporating additives therein may be formed into various moldedarticles differing in shape according to molding methods customarilyadopted for ordinary synthetic resins, such as the extrusion moldingmethod, the injection molding method, and the compression moldingmethod. The molding temperature differs according to the polymerizationdegree of the polymer and other factors. If the polymerization degree isrelatively high, the molding temperature is ordinarily 300° C. to 350°C.

The polymer of the present invention is substantially linear and issoluble in solvents. Accordingly, even a polymer having a highpolymerization degree, which is inferior in the melt moldability, caneasily be molded into a film according to the casting method using asolvent.

Since the polymer of the present invention has excellent properties asdescribed above, it can be used in various fields. For example, thepolymer is effectively used not only as a flame retardant but also forthe production of films, sheets, and various molded articles.Especially, the polymer of the present invention can widely be used as ahot water pipe, a steam sterilization vessel, a housing and parts in theelectrical and electronic fields, an interior part of an automobile orairplane, a sliding part, a gear, an insulating material, and the like.

(G) Examples, Comparative Examples, and Application Examples

The present invention will now be described in detail with reference tothe following examples and application examples.

Incidentally, in the examples, the polymerization degree was determinedbased on the number average molecular weight Mn calculated from themolecular weight measured by the osmometry or light scattering methodand the molecular weight distribution (Mw/Mn) determined by gelpermeation chromatography (the measurement method will be describedhereinafter).

In the application examples, the yield strength and elongation weremeasured according to the method of ASTM D-638-58T, and the Izod impactstrength (notched) was measured according to the method of ASTMD-256-56. The Vicat softening temperature was measured according to themethod of ASTM D-1525, and the Rockwell hardness (M scale and R scale)was measured according to the method of ASTM D-785. In the examples,comparative examples, and application examples, the heat distortiontemperature was measured according to the method of ASTM D-648.

In the application examples, the inherent viscosity was calculated fromthe following formula with respect to a solution containing 0.5 g/100 mlof the polymer in dimethylformamide at a temperature of 20° C.: ##EQU1##wherein t stands for the flow-out time (seconds) of the polymersolution, t₀ stands for the flow-out time (seconds) of the solvent, andC stands for the concentration of the polymer solution (grams of thepolymer in 100 ml of the solution).

EXAMPLE 1

(A) Preparation of Alkali Metal Salt of Monomer (B)

A 500 ml capacity flask equipped with a stirrer, a thermometer, awater-cooling condenser-equipped continuous water trap, a droppingfunnel, and a nitrogen-introducing tube was charged with 18.26 g (0.08mole) of 2,2-bis(4-hydroxyphenyl) propane as the monomer (B), 200 ml(221 g) of chlorobenzene as the inert azeotropic solvent, and 60 ml (66g) of dimethylsulfoxide as the inert, highly polar solvent. Nitrogen gaswas bubbled in the content at room temperature (20° C.) to 60° C. tosufficiently replace the atmosphere of the reaction system withnitrogen. Then, 20.32 g (0.16 mole) of an aqueous solution of sodiumhydroxide as the alkali metal compound (the sodium hydroxideconcentration was 31.50% by weight) was dropped through the droppingfunnel and 5 ml of water was passed through the dropping funnel to washaway the solution of sodium hydroxide from the dropping funnel into theflask. The mixture was sufficiently stirred, and the liquid temperaturewas elevated with stirring and water was removed by azeotropicdistillation with chlorobenzene while distilled chlorobenzene wasreturned to the reaction system. A white precipitate was formed in thereaction mixture. Recycle of chlorobenzene was stopped, andchlorobenzene was removed by distillation from the reaction mixtureuntil 60 ml of chlorobenzene was left in the flask. Water in thereaction system was substantially completely removed.

(B) Preparation of Polymer

The reaction system was cooled to 80° C., and 28.48 g (0.08 mole) of3,3',4,4'-tetrachlorodiphenylsulfone (C4DPS) as the monomer (A) wasadded at one time. The temperature of the reaction system was graduallyelevated to distill off chlorobenzene in the reaction system, andpolymerization was carried out at a temperature of 150° C. to 155° C.for 2 hours with stirring. Then, at a temperature of 150° C., methylchloride was bubbled into the polycondensation solution over a period of30 minutes to cap the polymer ends. The reaction system was naturallycooled to about 60° C., and 300 ml of chlorobenzene was added and theprecipitated salt was separated by filtration using a glass filter.Then, about 500 ml of methyl alcohol was added to precipitate the formedpolymer. The polymer was dissolved by using about 400 ml of methylenechloride as a good solvent for the polymer, and about 600 ml of methylalcohol (non-solvent) was added to the solution to precipitate thepolymer. The polymer was separated by filtration and washed. Thisoperation was conducted once more to purify the obtained polymer. Then,the methylene chloride solution of the polymer was poured into methylalcohol to finally recover a polymer in the form of foamed fibers. Thepolymer was dried at a temperature of 130° C. under reduced pressure toobtain 38.8 g (94.8% of the theoretical value) of a white polymer(hereinafter referred to as "polycondensate (a)"). The polymerizationdegree (n) was 58.

(C) Properties of Polymer

When the elementary analysis of the polycondensate (a) was performed,the following results were obtained.

Calculated:

C=63.41% by weight, H=3.44% by

weight, C1=13.86% by weight.

Found:

C=63.34% by weight, H=3.89% by

weight, C1=13.80% by weight.

From the foregoing results and analysis results described below, it wasconfirmed that the recurring units of the polycondensate (a) wererepresented by the following structural formula: ##STR7##

A solution of the polycondensate (a) in chloroform was subjected to gelpermeation chromatography using a column (Showdex A80-M (Trademark)supplied by Showa Denko). A single peak was observed. Namely, anypossibility of the presence of an ultra-high-molecular-weight polymersuggesting a branched structure was not found.

The polycondensate (a) was soluble in methylene chloride, chloroform,1,1,2,2-tetrachloroethane, chlorobenzene, and o-dichlorobenzene but wasswollen in acetone. However, the polycondensate (a) was not changed inn-hexane and methyl alcohol (not dissolved or swollen).

EXAMPLE 2

A solution of the disodium salt of the monomer (B) in the liquid mixtureof dimethylsulfoxide and chlorobenzene, which was prepared in the samemanner as described in (A) of Example 1 (the concentration was adjustedby conducting the hydration treatment in the same manner as described in(A) of Example 1), was cooled to 110° C. A solution (liquid temperatureof 80° C.) formed by dissolving 25.73 g (0.08 mole) of3,3',4-trichlorodiphenylsulfone (C3DPS), instead of3,3',4,4'-tetrachlorodiphenylsulfone (C4DPS) used as the monomer (A) in(B) of Example 1, in 30 ml of chlorobenzene was added at one time to thecooled solution. Just after addition of the above solution, the liquidreaction mixture was colored a light yellow. The temperature of theliquid reaction mixture was gradually elevated and chlorobenzene wasdistilled off until 5 ml of chlorobenzene was left in the liquidreaction mixture. The reaction was carried out at a temperature of 145°C. to 155° C. for 1 hour to obtain an apparently homogeneous solutionhaving a high viscosity. Then, 20 ml of anhydrous chlorobenzene wasadded to the solution, and the liquid temperature was maintained at 130°C. and methyl chloride was blown into the liquid for 30 minutes to stopthe polymerization. Then, the obtained polymer was purified and dried inthe same manner as described in (B) of Example 1 to obtain 36.7 g (96.2%of the theoretical value) of a polymer (hereinafter referred to as"polycondensate (b)") in the form of white foamed fibers. Thepolymerization degree (n) was 78.

When the polycondensate (b) was subjected to the elementary analysis,the following results were obtained.

Calculated:

C=67.99% by weight, H=4.44% by weight,

C1=7.43% by weight.

Found:

C=67.87% by weight, H=4.35% by weight,

C1=7.51% by weight.

From the foregoing results and analysis results described below, it wasconfirmed that the recurring units of the polycondensate (b) wererepresented by the following structural formula: ##STR8##

When the polycondensate (b) was subjected to gel permeationchromatography as in case of the polycondensate (a), no possibility ofthe presence of an ultra-high-molecular-weight polymer suggesting abranched structure was found.

The solubility characteristics of the polycondensate (b) were similar tothose of the polycondensate (a). The polycondensate (b) was soluble inmethylene chloride, chloroform, 1,1,2,2-tetrachlorroethane,chlorobenzene, and o-dichlorobenzene and swollen in acetone. Thepolycondensate (b) was not dissolved or swollen in n-hexane, methylalcohol, and ethyl alcohol.

The polycondensate (a) obtained in Example 1 and the polycondensate (b)obtained in Example 2 were subjected to infrared absorption spectrumanalysis. The results are shown in FIGS. 1 and 2, respectively.

From FIGS. 1 and 2, it is seen that in each of the polycondensateobtained in Example 1 and the polycondensate (b) obtained in Example 2,there are present absorptions attributed to --SO₂ -- at 1340 cm⁻¹ and1280 to 1260 cm⁻¹ and an absorption attributed to the aromatic etherlinkage at 1280 to 1260 cm⁻¹. Furthermore, in case of the polycondensate(a), two sharp absorptions are observed at about 1500 cm⁻¹, whichsuggests the presence of two kinds of benzene nuclei. In case of thepolycondensate (b), three sharp absorptions are observed at about 1500cm⁻¹, which suggests the presence of three kinds of benzene nuclei. Ineach of the polycondensates (a) and (b), absorption of the benzenenucleus attributed to the following structure (A) is observed at 1510cm⁻¹. In the polycondensate (a), one strong and sharp absorption of thebenzene nucleus attributed to the following structure (B) is shifted toa lower wave number, that is, 1480 cm⁻¹, by the influence of chlorine(C1). In the polycondensate (b), not only an absorption at 1480 cm⁻¹ butalso an absorption of the benzene nucleus attributed to the followingstructure (C), which is not observed in the polycondensate (a), isobserved: ##STR9##

The polycondensate (a) obtained in Example 1 and the polycondensate (b)obtained in Example 2 were subjected to the nuclear magnetic resonanceabsorption spectrum at a temperature of 35° C. in deuterated chloroformas the solvent at a concentration of 1% by using a nuclear magneticresonance apparatus (supplied by Hitachi, Ltd.) of 60 MHz.

It is supposed that the recurring units of the polycondensate (a) havethe above-mentioned structure formula; namely, it is considered that thestructure is as follows: ##STR10##

It is necessary and sufficient if the manner of substitution of3,3',4,4'-tetrachlorodiphenylsulfone (monomer (A)) in the polycondensate(a) is confirmed. Accordingly, the presence of three protons Ha, Hb, andHc will now be quantitatively proved.

Ha was observed as a doublet at a δ value of 7.98 ppm. Namely, this issplit in two small lines by the coupling with Hb.

Hb was observed as a quadrilet as a δ value of 7.69 ppm. Namely, this isgreatly split in two doublets by the coupling with Hc, and thesedoublets are split in two small lines, respectively, by coupling withHa.

Hc was observed as a doublet at a δ value of 7.25 ppm. This boublet isdue to coupling with Hb.

As is seen from the foregoing, only signals corresponding to Ha and Hbare observed in the range of δ values of from 8.0 to 7.5. This meansthat the chlorine atom at the para-position to the SO₂ group isselectively reacted. If both the chlorine atoms at the para-position andmeta-position to the SO₂ group are reacted concurrently, protons of thebenzene nuclei on both the sides of the SO₂ group are not simply dividedinto three kinds.

Furthermore, a signal of the proton of the CH₃ group was observed at a δvalue of 1.70 ppm. If it is supposed that the area of this signalcorresponds to six protons, each of the signal areas of the protons Haand Hb corresponds to 2.0 protons within an error.

In connection with other protons Hc, Hd, and He, signals of deuteratedchloroform used as the solvent appeared at a δ value of 7.23 ppm, and,therefore, the quantitative determination was not performed.

By the foregoing results, it was proved that the recurring units of thepolycondensate (a) are represented by the above structural formula.

As in the case of the polycondensate (a), it is supposed that therecurring units of the polycondensate (b) have the above-mentionedstructural formula; namely, it is considered that the structure is asfollows: ##STR11##

It is necessary and sufficient if the manner of substitution of3,3',4-trichlorodiphenylsulfone (monomer (A)) in the polycondensate (b)is confirmed. Accordingly, the presence of five protons Ha, Hb, Hc, Hd,and He will now be quantitatively proved.

Ha was observed as a doublet at a δ value of 7.98 ppm, and thiscorresponded to the proton Ha of the polycondensate (a).

Hb was observed as a quadrilet at a δ value of 7.69 ppm, and thiscorresponded to the proton Hb of the polycondensate (a).

Hd was observed as an apparent doublet at a δ value of 7.83 ppm. Namely,the doublet due to coupling with He was observed. If the resolving poweris increased, coupling of two Hd protons with each other will also beobserved, though the signal is small.

Furthermore, Hc was observed as a doublet at a δ value of 7.25 ppm, andHe was observed as a doublet at a δ value of 7.23 ppm.

When the numbers of the respective protons are counted based on theproton of the CH₃ group observed at a δ value of 1.70 ppm, the sum ofone proton Ha and the protons Hb and Hd having the signals overlappedthereto corresponds to three protons within an error.

By the foregoing results, it was proved that the recurring units of thepolycondensate (b) are represented by the above structural formula.

From the above-mentioned results of the infrared absorption spectrumanalysis, nuclear magnetic resonance absorption analysis, elementaryanalysis, and gel permeation chromatography, it is apparent that therecurring units of the polycondensate (a) obtained in Example 1 and therecurring units of the polycondensate (b) obtained in Example 2 arerepresented by the above-mentioned structural formulae, respectively.

Application Example

A polymer corresponding to the polycondensate (a) was prepared bycarrying out polymerization in a scale 20 times the scale of Example 1(the molar ratio and polymerization conditions were the same as inExample 1). Furthermore, a polymer corresponding to the polycondensate(b) was prepared by carrying out polymerization in a scale 20 times thescale of Example 2 (the molar ratio and polymerization conditions werethe same as in Example 2). These polycondensates (a) and (b) werepurified and dried in the same manner as described in (B) of Example 1.For comparison, a polymer (hereinafter referred to as "polycondensate(c)") having an inherent viscosity of 0.36 and having recurring unitsrepresented by the following formula: ##STR12## was prepared. Theproperties of these three polymers were examined.

More specifically, the polycondensates (a), (b), and (c) werehot-pressed (compression-molded) under compression of 100 kg/cm² for 10minutes by using a hot press maintained at 330° C. Each of the obtainedpressed plates was transparent and had a light yellow color. Thephysical properties of the pressed plates were measured. The obtainedresults are shown in Table 1.

                  TABLE 1                                                         ______________________________________                                                       Polycon-  Polycon-  Polycon-                                   Item           densate (a)                                                                             densate (b)                                                                             densate (c)                                ______________________________________                                        Yield strength (kg/cm.sup.3)                                                                 850       775       692                                        Elongation (%)  60        50       120                                        Izod impact strength                                                                         3.0 to 3.8                                                                              4.0 to 4.3                                                                                 6.2                                     (notched) (kg · cm/cm)                                               Heat distortion tempera-                                                                     177       175       174                                        ture (under load of 18.6                                                      kg/cm.sup.2) (°C.)                                                     Vicat softening point (°C.)                                                           192       191       189                                        Rockwell hardness                                                                            M-95,     M-85,     M-85,                                                     R-127     R-126     R-121                                      ______________________________________                                    

From the results shown in Table 1, it is seen that the polymer of thepresent invention has a much higher yield strength than that of thecomparative polycondensate (c) having no chlorine substituent on thenucleus and the polymer of the present invention has a higher hardness.

When the pressed plate of the polycondensate (a) was held in airmaintained at 350° C. for 1 hour, no particular change of the color wasobserved. When this fact is taken into consideration in the light ofdata shown in Table 1, it is understood that the polymer of the presentinvention is excellent in heat stability at a high temperatures eventhough it has chlorine atoms on the nucleus.

The combustibilities of the polycondensate (a) of the present inventionand the comparative polycondensate (c) were tested according to ULStandard. It was found that the combustibility of the polycondensate (a)was 94V-O, while the combustibility of the polycondensate (c) was 94V-1.

EXAMPLE 3

An alkali metal salt of the monomer (B) was prepared under the sameconditions as described in (A) of Example 1, except that 22.38 g (0.16mole) of an aqueous solution of potassium hydroxide (the concentrationof potassium hydroxide was 40.12% by weight) was used as the aqueoussolution of the alkali metal compound instead of the aqueous solution ofsodium hydroxide used in (A) of Example 1. Water was completely removedfrom the reaction system containing this alkali metal salt by azeotropicdistillation with chlorobenzene, and polymerization was carried out inthe same manner as described in (B) of Example 1 (the polymerizationtemperature was 155° C. and the polymerization time was 45 minutes). Inthe same manner as described in (B) of Example 1, polymerization wasstopped and the obtained polymer was purified and dried to obtain 39.6 g(96.8% of the theoretical value) of a polymer in the form of a whitefoamed fiber. The polymerization degree of this polymer was 130.

EXAMPLE 4

A 500 ml-capacity flask equipped with a stirrer, a thermometer, awater-cooling condenser-equipped continuous water trap, and anitrogen-introducing tube was charged with 19.02 g (0.05 mole) of adisodium salt hexahydrate of 2,2-bis(4-hydroxyphenyl)propane as thealkali metal salt of the monomer (B), 17.80 g (0.05 mole) of3,3',4,4'-tetrachlorodiphenylsulfone as the monomer (A), 40 ml ofdimethylsulfoxide as the inert, highly polar solvent, and 160 ml ofchlorobenzene as the inert azeotropic solvent. A liquid-accumulatingportion of the continuous water trap was filled with 40 ml ofchlorobenzene. At a temperature of 60° C., the mixture was stirred for20 minutes while bubbling nitrogen in the reaction system. Thetemperature in the reaction system was gradually elevated, and theliquid was refluxed at 120° C. to 135° C. to trap water continuously.When about 4.7 ml of water was distilled off, reflux of chlorobenzenewas stopped, and chlorobenzene and water were distilled off from thereaction system. With this distillation, the temperature of the reactionmixture gradually rose and arrived at 155° C. over a period of 1.5hours. At this temperature, the polymerization was conducted for 3hours. The liquid reaction mixture became viscous. To this viscousliquid was added 0.72 g (0.0025 mole; 5 mole % based on the monomer (A))of 4,4'-dichlorophenylsulfone. At the above temperature, the reactionwas conducted for 1 hour. Then, the liquid reaction mixture wasnaturally cooled and diluted with 250 ml of chlorobenzene to precipitatethe formed salt, and the obtained polymer was purified and dried in thesame manner as described in (B) of Example 1 to obtain 24.8 g (97.0% ofthe theoretical value) of a white polymer. The polymerization degree ofthe polymer was 44.

EXAMPLE 5

A flask similar to the flask used in Example 4 was charged with 22.83 g(0.1 mole) of 2,2-bis(4-hydroxyphenyl) propane as the monomer (B),35.605 g (0.1 mole) of 3,3',4,4'-tetrachlorodiphenylsulfone as themonomer (A), 14.66 g of anhydrous potassium carbonate (purity of 99%) asthe alkali metal compound, 95 ml of dimethylsulfoxide as the inert,highly polar solvent, and 100 ml of chlorobenzene as the inertazeotropic solvent. Bubbling of nitrogen was initiated at roomtemperature (20° C.), and the temperature of the reaction system wasgradually elevated. Formed water was removed by azeotropic distillationwith chlorobenzene. When the total amount of the distillate wasincreased to 70 ml, no substantial distillation of water was observed.While distillation of chlorobenzene was further continued, thetemperature of the reaction system was elevated to 160° C. The reactionwas carried out at this temperature for 2.5 hours, whereby the solutionwas made viscous. Then, the polymerization was stopped by capping theends of the formed polymer in the same manner as described in (B) ofExample 1. Then, separation of the formed salt and purification anddrying of the obtained polymer were performed in the same manner asdescribed in (B) of Example 1 to obtain 49.3 g (96.4% of the theoreticalvalue) of a polymer in the form of a white foamed fiber. Thepolymerization degree of the polymer was 190.

EXAMPLE 6

A dialkali metal salt of the monomer (B) was prepared in the same manneras described in (A) of Example 1 except that 60 ml oftetramethylenesulfone was used as the inert, highly polar solventinstead of dimethylsulfoxide used in (A) of Example 1, and 200 ml oftoluene was used as the inert azeotropic solvent instead ofchlorobenzene used in (A) of Example 1. Then, water in the reactionmixture was continuously removed by azeotropic distillation with tolueneto collect about 21 ml of water in the water trap. At this point, thedialkali metal salt was dispersed in the form of a white slurry in themixture of the solvents. A minute amount of water was distilled off fromthe reaction system together with toluene, and about 160 ml of tolueneas a whole was distilled off.

The reaction system was cooled to 100° C., and3,3',4,4'-tetrachlorodiphenylsulfone in the same amount as used in (B)of Example 1 was added at one time. The temperature of the reactionsystem was elevated while excessive toluene was distilled off. Thereaction was carried out at 210° C. for 1 hour and at 220° C. for 1hour, whereby the slurry-like reaction solution was converted to ahomogeneous viscous liquid. The reaction liquid was cooled to 160° C.and 1.15 g (0.004 mole) of 4,4'-dichlorodiphenylsulfone was added. Atthis temperature, the terminal-capping reaction was carried out for 1hour. After the polymerization, the obtained polymer was purified anddried in the same manner as described in (B) of Example 1 to obtain 38.4g (93.9% of the theoretical value) of a polymer in the form of alight-yellow foamed fiber. The polymerization degree of the polymer was40.

EXAMPLE 7

An alkali metal salt of the monomer (B) was prepared and dehydrated inthe same manner as in Example 5 except that 11.78 g (0.11 mole) ofanhydrous sodium carbonate having a purity of 99% was used as the alkalimetal compound instead of anhydrous potassium carbonate used in Example5. A polymer was prepared under the same conditions as in Example 5,except that the polymerization was carried out for 8 hours at atemperature of 180° C. Then, the ends of the obtained polymer werecapped and the polymer was purified and dried in the same manner asdescribed in Example 5 to obtain 48.8 g (95.5% of the theoretical value)of a polymer in the form of a light-yellow foamed fiber. Thepolymerization degree of the polymer was 132.

EXAMPLE 8

An alkali metal salt of the monomer (B) was prepared under the sameconditions as described in (A) of Example 1, except that 16.02 g (0.08mole) of 1,1-bis(4-hydroxyphenyl) methane was used as the monomer (B)instead of 2,2-bis(4-hydroxyphenyl) propane used in (A) of Example 1. Apolymer was prepared in the same manner as described in (B) of Example1, except that this alkali metal salt was used and the polymerizationwas conducted at 145° C. to 155° C. for 4 hours. Then, the terminal endsof the obtained polymer were capped and the polymer was purified anddried in the same manner as described in (B) of Example 1 to obtain36.74 g (95.0% of the theoretical value) of a polymer in the form of awhite fiber. The polymerization degree of the polymer was 77, and theglass transition point was 183° C. In the same manner as described in(C) of Example 1, it was confirmed that the recurring units of thepolymer had the following structural formula: ##STR13##

The polymer was compression-molded under a compression of 100 kg/cm² at300° C. for 10 minutes, and a film having a thickness of 0.2 mm wasobtained.

EXAMPLE 9

The polymerization was carried out under the same conditions asdescribed in Example 3 except that 21.47 g (0.08 mole) of1,1-bis(4-hydroxyphenyl)cyclohexane was used as the monomer (B) insteadof 2,2-bis(4-hydroxyphenyl)propane used in Example 3. The terminals ofthe obtained polymer were capped, and the polymer was purified and driedin the same manner as described in Example 3 to obtain 42.8 g (97.0% ofthe teoretical value) of a polymer in the form of a white fiber. Thepolymerization degree of the polymer was 89. A light-yellow transparentfilm having a thickness of 0.2 mm was prepared by compression-moldingthe obtained polymer under compression of 100 kg/cm² at 320° C. for 10minutes. The glass transition temperature of the polymer was 204° C.

In the same manner as described in (C) of Example 1, it was confirmedthat the polymer had recurring units represented by the followingstructural formula: ##STR14##

EXAMPLE 10

A flask similar to the flask used in (A) of Example 1 (400 ml ofchlorobenzene was filled in the water trap for continuously trappingwater) was charged with 100 ml of dimethylsulfoxide as the inert, highlypolar solvent and 200 ml of chlorobenzene as the inert azeotropicsolvent, and nitrogen was bubbled in the charge of the flask for 15minutes. Then, 11.0 g (0.10 mole) of hydroquinone was added as themonomer (B) and the temperature was elevated to 80° C. while bubblingnitrogen. At this temperature, 22.35 g (0.20 mole) of an aqueoussolution of potassium hydroxide (the concentration of potassiumhydroxide was 50.20% by weight) was dropped into the reaction liquidwith stirring over a period of 5 minutes. The dropping funnel was washedwith 5 ml of water, and the washing liquid was added to the reactionliquid (all of the foregoing operations were conducted in a nitrogen gasatmosphere). The temperature of the reaction system was elevated, andwater was continuously removed by azeotropic distillation withchlorobenzene. When the amount distilled of water was about 19 ml, thecontinuous reflux was stopped and the distillate was removed from thereaction system. When the total amount of distilled chlorobenzene was140 ml, the reaction system was cooled to 80° C., and a solution of32.16 g (0.10 mole) of 3,3',4-trichlorodiphenylsulfone is 40 ml ofchlorobenzene was added at one time. The temperature of the reactionsystem was elevated, and 130 ml of chlorobenzene was distilled off.Then, the polymerization was carried out at 155° C. and 4 hours toobtain a viscous liquid. The terminals of the obtained polymer werecapped in the same manner as described in (B) of Example 1. The reactionliquid was poured into water, the polymer was pulverized, and the formedsalt and the inert, highly polar solvent were extracted by using heatedwater then extracted by using heated acetone. Then, the residue wasdried under reduced pressure at a temperature of 150° C. to obtain 35.7g (99.5% of the theoretical value) of a light-brown flaky polymer. Thepolymerization degree of the obtained polymer was 80. A film having athickness of 0.2 mm was prepared by compression-molding the polymer at350° C. under compression of 100 kg/cm² for 10 minutes. The glasstransition point of the polymer was 206° C. In the same manner asdescribed in (C) of Example 1, it was confirmed that the recurring unitsof the polymer had the following structural formula: ##STR15##

EXAMPLE 11

The polymerization was carried out under the same conditions as inExample 10, except that 20.2 g (0.10 mole) of 4,4'-dihydroxydiphenylether was used as the monomer (B) instead of hydroquinone used inExample 10. In the same manner as described in Example 10, the terminalsof the obtained polymer were capped and the polymer ws purified anddried. As the result, 43.8 g (97.1% of the theoretical value) of alight-yellow fibrous polymer was obtained. The polymerization degree ofthe polymer was 74, and the glass transition point was 177° C. In thesame manner as described in (C) of Example 1, it was confirmed that therecurring units of the polymer had the following structural formula:##STR16##

Comparative Example 1

In the same manner as described in (A) of Example 1, a solution of adisodium salt of 2,2-bis(4-hydroxyphenyl)propane in a liquid mixture(mixed solvent) of dimethylsulfoxide and chlorobenzene was prepared. Thesolution was dehydrated in the same manner as in (A) of Example 1, andsubstantially all of chlorobenzene was distilled off. Then, the liquidtemperature was elevated to 155° C.

Then, a solution of 28.48 g (0.08 mole) of 3,3',4,4'-tetrachlorodiphenylsulfone in 30 ml of chlorobenzene was droppedinto the resulting apparently transparent solution over a period of 20minutes in a nitrogen gas atmosphere. During the dropwise addition, thereaction temperature was maintained above 150° C. and chlorobenzene wasdistilled off from the reaction system. After completion of the dropwiseaddition, the reaction mixture was stirred at 155° C. for 5 minutes, andthe viscosity of the polymerization mixture was abruptly increased andstirring became impossible. The reaction product was naturally cooled,and 300 ml of chlorobenzene was added to the reaction product. Theproduct was not dissolved, but became swollen in an agar-like state. Theproduct was also insoluble in dimethylformamide.

From the foregoing results, it is understood that if the monomer (A)used in the present invention is gradually added to a solution of adialkali metal salt of the monomer (B) at a relatively high temperature,a valuable, substantially linear polymer as obtained according to thepresent invention cannot be formed at all.

Comparative Example 2

A solution of a disodium salt of 2,2-bis(4-hydroxyphenyl)propane in aliquid mixture (mixed solvent) of dimethylsulfoxide and chlorobenzenewas prepared in the same manner as described in (A) of Example 1. In thesame manner as described in (A) of Example 1, the solution wasdehydrated. Distillation was carried out until 60 ml of chlorobenzenewas left in the liquid mixture.

The liquid reaction mixture was cooled to 80° C., and 27.06 g (0.076mole) of 3,3',4,4'-tetrachlorodiphenylsulfone (95 mole % based on thedisodium salt of 2,2-bis(4-hydroxyphenyl)propane) was added at a time tothe liquid reaction mixture. The temperature of the reaction mixture waselevated and excessive chlorobenzene was distilled off at 135° C. to155° C. The reaction was carried out at 155° C. After a lapse of 40minutes, the formed polymer clung and adhered to the stirrer, andstirring became impossible. The polymer was not dissolved inchlorobenzene, chloroform, and dimethylformamide but only swollentherein.

From the foregoing results, it is apparent that when a small amount (95mole %) of the monomer (A) is used for the dialkali metal salt of themonomer (B) and the polymerization is carried out, a valuable,substantially linear polymer as obtained according to the presentinvention cannot be obtained at all.

Incidentally, in the accompanying drawings, FIG. 1 shows the infraredabsorption spectrum of the polycondensate (a) obtained in Example 1 andFIG. 2 shows the infrared absorption spectrum of the polycondensate (b)obtained in Example 2.

We claim:
 1. A substantially linear, chlorine-containingpolyether-sulfone polymer consisting essentially of repeating unitsrepresented by the following general formula (I): ##STR17## wherein Xand Y stand for a hydrogen atom or a chlorine atom, with the provisothat at least one of X and Y is a chlorine atom, Q stands for a directbond, --O--, --S-- or a divalent aliphatic or alicyclic hydrocarbongroup in which the carbon number is an integer of from 1 to 6, m is 0 or1, and n is an integer of from 10 to
 1000. 2. A substantially linear,chlorine-containing polyether-sulfone polymer as set forth in claim 1,wherein one of X and Y is a hydrogen atom and the other is a chlorineatom.
 3. A substantially linear, chlorine-containing polyether-sulfonepolymer as set forth in claim 1, wherein each of X and Y is a chlorineatom.
 4. A substantially linear, chlorine-containing polyether-sulfonepolymer as set forth in claim 1, wherein X is a chlorine atom and Y is ahydrogen or chlorine atom, they are distributed statistically along themain chain, and the number l of the chlorine atom per recurring unit ofthe formula (I) is in the range of 1<l<2.
 5. A substantially linear,chlorine-containing polyether-sulfone polymer as set forth in any ofclaims 1, 2, 3 or 4, wherein Q is ##STR18## and m is
 1. 6. A process forthe preparation of a chlorine-containing polyether-sulfone polymer,which comprises adding at least one aromatic tri- or tetra-haliderepresented by the following general formula (III): ##STR19## wherein Xand Y stand for a hydrogen atom or a chlorine atom, with the provisothat at least one of X and Y is a chlorine atom,at a time to asubstantially anhydrous mixture of at least one dialkali metal salt of adihydric phenol represented by the following general formula (II):##STR20## wherein Q stands for a direct bond, --O--, --S-- or a divalentaliphatic or alicyclic hydrocarbon group in which the carbon number isan integer of from 1 to 6, and m is 0 or 1, and an inert, highly polarsolvent at a temperature of 0° C. to 140° C. in an amount of 98 to 105moles per 100 moles of said dialkali metal salt, and heating the mixtureto effect reaction.
 7. A process for the preparation of achlorine-containing polyether-sulfone polymer, which comprisescontacting and reacting 1 mole of a dihydric phenol represented by thefollowing general formula (II): ##STR21## wherein Q stands for a directbond, --O--, --S-- or a divalent aliphatic or alicyclic hydrocarbongroup in which the carbon number is an integer of from 1 to 6, and m is0 or 1,with 2 moles of an alkali metal hydroxide in the presence of aninert, highly polar solvent and an inert solvent capable of azeotropicdistillation with water to form a dialkali metal salt of said dihydricphenol, removing water in the resulting liquid mixture by azeotropicdistillation with said inert azeotropic solvent to render the mixturesubstantially anhydrous and render said dialkali metal saltsubstantially insoluble in the liquid mixture, adding an aromatic haliderepresented by the following general formula (III): ##STR22## wherein Xan Y stand for a hydrogen atom or a chlorine atom, with the proviso thatat least one of X and Y is a chlorine atom, to the liquid mixture, andcarrying out polymerization while distilling off the inert azeotropicsolvent by heating.
 8. A process for the preparation of achlorine-containing polyether-sulfone polymer, which comprises heating100 moles of a dihydric phenol represented by the following generalformula (II): ##STR23## wherein Q stands for a direct bond, --O--, --S--or a divalent aliphatic or alicyclic hydrocarbon group in which thecarbon number is an integer of from 1 to 6, and m is 0 or 1,98to 105moles of an aromatic tri- or tetra-halide represented by the followinggeneral formula (III): ##STR24## wherein X and Y stand for a hydrogenatom or a chlorine atom, with the proviso that at least one of X and Yis a chlorine atom, and 100 to 200 moles of an alkali metal carbonate or200 to 400 moles of an alkali metal hydrogencarbonate in the presence ofan inert, highly polar solvent and an inert azeotropic solvent tosubstantially form a dialkali metal salt of said dihydric phenol andeffecting polymerization while distilling off formed water by azeotropicdistillation with the inert azeotropic solvent or after saiddistillation.